Cleaning of whey protein and milk salts soiled on DLC coated surfaces at high-temperature Original Research Article

New surface coatings offer great potential to reduce deposition on heat exchanger surfaces and to improve their cleanability. However, the surface coating must be resistant to thermal, chemical and mechanical stress during processing and cleaning. The aims of this investigation were to evaluate the potential of DLC (diamond-like carbon) coatings to enhance the cleaning efficiency of milk soil and to identify surface parameters influencing its cleaning behavior. The coated surfaces, namely DLC and modified DLC (SICAN and SICON®), were soiled by whey protein and milk salts at ultra-high temperature. The deposit removal, using 0.5% w/w NaOH, was monitored by consequential changes in heat transfer resistance and protein concentration in the cleaning solution. Different cleaning profiles and cleaning rates occurred for the tested surfaces. The results showed that the polar contribution to surface energy is the main factor influencing the deposit’s adhesion strength and therefore its removal.